1. Technical Field
This invention concerns a method for machining piston rings—compression piston rings in particular—that are in accordance with a mate-forming part of the initial patent claim
2. Related Art
In many cases, piston rings are produced in such a way that they are cylindrically machined on their outer peripheral surface. External turning is subsequently used to produce a contour that will be needed at a later point; this contour is referred to as a bearing surface contour. A wear-resistant layer is then applied to this above-mentioned bearing surface contour—this could, for example, be a chromium layer—which is reflected on the machined contour and on the one that follows. The final running surface geometry is created by cylindrical lapping. In order to execute this work step within a reasonable period of time and with the correct convexity, the contact surface must already have a contour at this point that is very close to the finished contour.
The external turning work step for producing the desired contour on the outside peripheral surface is extremely time and cost intensive.
DE 31 44 335 C2 shows a process for producing rotationally symmetrical work pieces—piston rings in particular—that are provided with a wear-resistant layer, whereby the work pieces are packetized and centrally clamped onto a mandrel, and the outer peripheral surface is then coated with a wear-resistant layer, and the package is again separated into its individual work pieces. Before the coating process, the packetized work pieces are scanned in the axial direction, whereby the axial position of each contact surface between the individual work pieces is determined and stored, and this data is made available to one or several cutting tools for detecting the contact surfaces after the work pieces have been coated.
The DE 198 09 659 C1 method for producing piston rings—for the internal combustion engine in particular—is already known, whereby this method taps individual rings on non-circular connectors consisting of metallic work pieces. The bushings are produced by thermally spraying spray material onto the outer surface of a mandrel serving as a mould, whereby the mandrel has an impact mark on the peripheral surface, and a layer that functions as a sliding layer is applied to the generated lateral surface on the bushings, and the piston rings for the bushing are subsequently tapped.